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Carbon Dioxide and Methane in the North American Great Lakes

Fernandez, Julianne M
http://orcid.org/0000-0001-5137-6620
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504868932301161

Abstract Details

2017, MS, University of Cincinnati, Arts and Sciences: Geology.
Recently, there has been considerable interest on the potential impacts of lakes, rivers and other inland waters on the global carbon (C) budget. In the past, these inland waters were commonly unaccounted for, but it is now known that lakes are a substantial part of the global C cycle. The North American Great Lakes are the largest freshwater system on Earth, but C dynamics in these large lakes are currently understudied. For example, it is not known whether the Great Lakes are a source for atmospheric C like smaller lakes, or a sink for C like in ocean systems. This is particularly important to study as atmospheric greenhouse gas concentrations increase and temperatures on Earth warm, because aquatic ecosystems may experience undocumented feedbacks, which have the potential to alter the Great Lakes C cycle. Here, I present the results of two modern-day studies of the C cycle of the North American Great Lakes. In chapter one, I present the results of a 13-month study of methane emissions from Lake Erie. I measured methane surface fluxes throughout the lake once every season and calculated a weighted area flux to estimate annual emissions. I found that the largest methane emissions were in the western basin. The highest rates co-occur with the highest rates of nutrient loading and algae blooms in Lake Erie. The annual lake-wide estimate indicated that methane emissions are driven by late spring and summer fluxes. Winter emissions were similar between the lake basins, indicating minimal emissions from natural gas wells and pipelines, in contrast to previous work. This work indicates Lake Erie is a methane emissions source almost all year round and is a possible positive feedback to increasing precipitation. In chapter two, I present the results of a study of carbon dioxide emissions from Lake Superior, Lake Michigan, and Lake Erie. During the summer of 2016, pH, alkalinity, and carbon stable isotopic ratios of dissolved inorganic carbon (in Lake Erie only) were measured in surface and bottom water. I found that surface water carbon dioxide emissions of the lakes were relatively small negative fluxes or near equilibrium with the atmosphere. Our data indicated that higher DIC concentrations have more depleted carbon isotopic signatures in bottom waters in Lake Erie indicating that methane is a substrate for respiration. These results indicate that as carbon dioxide concentrations increase in the atmosphere, the Great Lakes may be vulnerable to acidification, which may affect native and invasive species health in the Great Lakes in unpredictable ways. Overall, these studies indicate that the North American Great Lakes have a C cycle that is vulnerable to anthropogenic perturbations such as climate warming, increasing precipitation, and increasing atmospheric carbon dioxide concentrations. Since the Great Lakes are the most intensively utilized freshwater systems on Earth for both water and food resources, it is important to understand the C cycle in this system in the face of forthcoming changes that could affect these resources.
Amy Townsend-Small, Ph.D. (Committee Chair)
Carlton Brett, Ph.D. (Committee Member)
Yurena Yanes, Ph.D. (Committee Member)
77 p.
Geology
Great Lakes; Methane; Carbon dioxide; Climate Change; Natural gas; algae blooms

Recommended Citations

Citations

  • Fernandez, J. M. (2017). Carbon Dioxide and Methane in the North American Great Lakes [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504868932301161

    APA Style (7th edition)

  • Fernandez, Julianne. Carbon Dioxide and Methane in the North American Great Lakes. 2017. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504868932301161.

    MLA Style (8th edition)

  • Fernandez, Julianne. "Carbon Dioxide and Methane in the North American Great Lakes." Master's thesis, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1504868932301161

    Chicago Manual of Style (17th edition)

ucin1504868932301161
172
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This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12